The present invention describes new compounds in which the pharmacophores of quinolone and oxazolidinone are chemically linked together through a linker that is stable under physiological conditions and a pharmaceutical antibacterial composition containing these compounds. These dual action compounds are useful antimicrobial agents effective against a variety of human and veterinary pathogens including Gram positive aerobic bacteria such as multiply-resistant staphylococci, streptococci and enterococci as well as Gram negative bacteria such as Moraxella catarrhalis and Haemophilius influenza and anaerobic organisms such as bacteroides spp. and Clostridia spp. species and acid-fast organism such as Mycobacterium tuberculosis, Mycobacterium avium spp.
The intensive use of antibiotics has exerted a selective evolutionary pressure on microorganisms to produce genetically based resistance mechanisms. Modern medicine and socioeconomic behavior exacerbates the problem of resistance development by creating slow growth situations for pathogenic microbes, e.g. artificial joints-related infections, and by supporting long-term host reservoirs, e.g. in immuno-compromised patients.
In hospital settings, an increasing number of strains of Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus sp., and Pseudomonas aeruginosa, major sources of infections, are becoming multi-drug resistant and therefore difficult if not impossible to treat:                S. aureus is β-lactam, quinolone and now even vancomycin resistant.        S. pneumoniae is becoming resistant to penicillin and even to new macrolides.        Enteroccocci are quinolone and vancomycin resistant and β-lactams were never efficacious against these strains. The only alternative is to use oxazolidinones but these compounds are not bactericidal and the safety margin is rather low. Further, even with these drugs, resistance already appears in clinical practice.        
In addition, microorganisms that are causing persistent infections are increasingly being recognized as causative agents or cofactors of severe chronic diseases like peptic ulcers or heart diseases.